"The dam is located on a geographic structure with an earthquake intensity of six degree. However, the dam has been designed with solidity to withstand an earthquake intensity of seven degree," said Cao at the press conference held one day before the completion of the construction of the dam’s main wall.

Cao representing the project undertaker said China has instituted emergency plans to guard the hydropower project against terrorist attacks by conventional weapons or nuclear weapons.

He said the mass dam wall made of concrete and reinforced steel bar would not be seriously marred by attacks by conventional weapons. In case of a nuclear attack, the project operator would discharge the water storage at orders from the authorities.

"It takes three to four days to empty the dam’s maximum storage capacity," said Cao.

The world’s largest hydropower project has a maximum water discharging capacity of 11,000 cubic meters per second.

In case of emergency water discharge, water would zigzag its way for 38 km from the dam site to the mouth of Xiling Gorge, one of the three gorges before entering the plain section in the middle reach of the river. The weakened discharging power would reduce flooding damages to the lower reach, where big metropolitans such as Wuhan, capital of Hubei and Shanghai on the river’s sea front are located.

China launched an anti-terror drill in November 2005 to optimize its emergency reaction scheme to protect the dam.

Responding to the dam’s safety, Zheng Shouren, chief engineer with the Yangtze River Water Resources Committee and academician with the Chinese Academy of Engineering, told reporters at the conference that even in case that the raging flood overbrimmed the dam’s wall, the sluice would smash down the concrete dam.

Launched in 1994, the construction of the Three Gorges dam measured 2,309 meters long and 185 meters above the sea level, has been undertaken in three phases on the middle reach of the Yangtze,China’s longest river.

Upon completion of the main dam wall on Saturday, the wall built with 16 million cubic meters of concrete will start to exert its flood-control function from this summer by storing water to 156 meters above the sea level from the current 135 meters.